IwaHanako?: I have used the 5-5 point attack/invasion to create a large center moyo and finish one of my sides. Even though I grant my opponent a large corner, in the situation I used it I already had at least one corner and some of another, the influence I gained in the center seemed well worth it. Comments?
Alex Weldon: It's also not an invasion. Invasion implies going under or between the opponent's stones. I suppose that if the 4-4 stone was part of a moyo, this could qualify as keshi (reduction). is a bad move, by the way, since it allows Black to hane at the head of two. Between to extend the other way. In any case, I'd be wary about playing such a move, because it allows Black to solidfy a very large corner territory.
IwaHanako?: Alex, I had the feeling it wasn't an invasion but what is it then?
Andre Engels: The normal move for would be at a, and indeed
is rarely good because Black's territory gets too large. It seems that professionals play
almost exclusively when on the top or right side there is some weak group that needs to run away.
IwaHanako?: I've rewritten my top since 'invented' looked kinda stupid (especially after you posted a professional game :/).
Slowman : My ideas:
This is the type of situation where one might see a professional play the 5-5 point shoulder hit.
Kajiwara Takeo (White) vs. Takemiya Masaki, Gosei League playoff 1977.
Charles The related 5-4 side contact play is seen in quite a number of pro games. Central fighting is one reason (as for the 5-5 shoulderhit); ko threats and ladder-breakers; but also sometimes as a kind of tesuji or sabaki play. It's generally a more interesting and flexible way, amongst unconventional plays round the 4-4 point.
There's a very nice example played by Karigane Junichi on Go Seigen in game 2 of their 1941 jubango. Go Seigen himself used it a number of times.
While we're here, what about the 3-4 contact play in the absence of an enclosure? (When there is an enclosure from the 4-4 point, this counts as joseki.)
This too occurs in pro games, though of course it is rare compared to playing an approach or the 3-3 invasion.
The common way to handle this in pro games seems to be on the outside,
and transpose to a 3-3 invasion sequence. So, what did White gain? Nothing, unless Black would prefer to block the other side after the 3-3 invasion. This naturally determines White's choice: 3-4 or 4-3? It should be such Black's resulting wall will be less useful.
I play this one often in handicap games: Black normally plays at
to take the corner, which allows a cross-cut.